When humid ambient air is compressed in an air compressor, thermodynamic processes occur that raise the air temperature and the dew point temperature. The dew point temperature as used herein is the temperature at which the relative humidity becomes 100% saturated and water vapor in the compressed air begins to condense into liquid.
The temperature increase can be significant enough to make the compressed air quite hot and unusable for many applications. To reduce the temperature of the compressed air to a usable range, certain air compressor systems use water or air cooled aftercoolers—named thus because they are located downstream from the compressor. Aftercoolers cool the compressed air to temperatures lower than the dew point. Compressed air exiting an aftercooler will contain significant amounts of condensed water droplets suspended in the air stream.
FIG. 1 depicts a typical air cooled aftercooler 10 with an external moisture separator 12. An external moisture separator 12 may take up a considerable amount of space and add weight and cost to a system.